Studies on the mechanism of action of glyceraldehyde as an inhibitor of erythrocyte sickling will be undertaken. The exact location of the lysine residues that react with glyceraldehyde will be determined by the techniques of peptide mapping and amino acid analysis. Other sites of adduct formation will be determined with labeled glyceraldehyde. The amount and sites of reaction as a function of the degree of oxygenation will also be evaluated. A collaboration with the laboratory in Seattle involved in the extracorporeal carbamylation of sickle erythrocytes by sodium cyanate will be initiated. We will measure the extent and sites of carbamylation of hemoglobin S on samples that they will send to us. Studies on the binding sites of inorganic anions on hemoglobin will be continued. Through experiments on specifically carbamylated derivatives of hemoglobin and by use of the abnormal hemoglobin Providence, we hope to determine whether or not Val-1 (alpha) and Lys-82 (beta) are the primary, oxygen-linked binding sites for chloride or phosphate.